Les argiles de la transition Cretace-Tertiaire au Guatemala, temoins d'un impact d'asteroide

The clay mineral assemblages of the Cretaceous-Tertiary (K/T) transition recorded in southern Peten sedimentary rocks have been studied in sections dated by calcareous nannofossils and foraminifera. The deposits contain cosmic and impact remains (iridium, Ni-rich magnetite, tektite) and typical Cheto smectites resulting from weathered tektites (glass spherules) produced by the Yucatan impact. The clay mineral assemblages are used for describing the palaeoenvironmental and tectonic evolution of southern Peten near the K/T boundary.